Polyetheroxy-substituted polyphosphazenes are known polymers. Their preparation is reported in Schulz et al. U.S. Pat. No. 4,258,173. They can be made by reacting a mono or polyetheroxy alkanol with a polyphosphonitrilic chloride in the presence of triethylamine to take up the evolved HCl. Alternatively, they can be made by reacting a sodium mono or polyetheroxy alkoxide with polyphosphonitrilic chloride in tetrahydrofuran. The polymers are utilized to form films, moldings, coatings, foams, and the like.
More recently a new utility for these polyetheroxy-substituted polyphosphazene has been reported by P. M. Blonsky, D. F. Shriver, P. Austin and H. R. Allcock, J. Am. Chem. Soc., 106, 6854 (1984). These authors describe solid electrolytes for use in electrical apparatus such as batteries which are made using polyetheroxy-substituted polyphosphazenes which are complexed with lithium, silver, sodium, rubidium, calcium, strontium, zinc, gadolinium or neodynium salts. In this electrolyte use it has been found that it is important that impurities be reduced to a very low level. When made by conventional methods, such as the reaction of sodium mono or polyetheroxy alkoxide with polyphosphonitrilic chloride, the resultant polymer contains high levels of mono or polyetheroxy alkanol, sodium and chloride impurities which are detrimental to the use of the polymer in electrolyte applications.